One thing there is worthy my Consideration, which is, that I find in my self innumerable _Ideas_ of certain things, which tho perhaps they _exist no where without_ Me, yet they cannot Be said to be _Nothing_; and tho they are _Thought_ upon by me at my _will_ and _pleasure_, yet they are not _made_ by _Me_, but have their own _True_ and _Immutable Natures_. As when, for example, * I _Imagine_ a _Triangle_, tho perhaps such a _Figure Exists no where_ out of my _Thoughts_, nor ever _will Exist_, yet the _Nature_ thereof is _determinate_, and its _Essence_ or Form is _Immutable_ and _Eternal_, which is neither _made_ by me, nor _depends_ on my mind, as appears for that many _properties_ may be _demonstrated_ of this Triangle, _viz._ That its three Angles are equal to two right ones, that to its Greatest Angle the Greatest side is subtended, and such like, which I now _clearly_ know whether _I will or not_, tho before _I_ never thought on them, when I _imagine_ a Triangle, and consequently they could not be invented by Me. And ’tis nothing to the purpose for me to say, that perhaps this _Idea_ of a Triangle came to me by the Organs of _sense_, because I have sometimes seen bodies of a _Triangular Shape_; for I can think of Innumerable other _Figures_, which I cannot suspect to have come in through my _senses_, and yet I can _Demonstrate_ various _properties_ of them, as well as of a _Triangle_, which certainly are all _true_, seeing I know them _clearly_, and therefore they are _something_, and not a meer _Nothing_, for ’tis Evident that _what is true is something_. And now I have sufficiently Demonstrated, that _what I clearly perceive, is True_; And tho I had _not demonstrated_ it, yet such is the _Nature_ of my _Mind_, that I could not but give my _Assent_ to what I _so_ perceive, at least, as long as I _so_ perceive it; and I remember (heretofore when I most of all relied on _sensible Objects_) that I held those _Truths_ for the most _certain_ which I _evidently_ perceived, such as are concerning _Figures_, _Numbers_, with other parts of _Arithmetick_, and _Geometry_, as also whatever relates to _pure_ and _abstracted Mathematicks_.